1. Field of the Invention
The present invention relates to an organic light emitting display device and a method of fabricating the same, and more particularly, to an organic light emitting display device with a pixel region having an increased step difference to facilitate the deposition of an organic layer using a laser-induced thermal imaging method.
2. Description of the Related Art
Among flat panel display devices, an organic light emitting display device has a fast response time shorter than 1 ms, consumes little power, and has a wide viewing angle range because it can emit light by itself. As a result, the organic light emitting display device has the advantage of a moving picture displaying medium regardless of the size thereof. Further, the organic light emitting display device can be fabricated at a low temperature, and its fabricating process is simple based on the existing semiconductor processing technology, thus attracting attention as a next generation flat panel display device.
According to materials and processes, the organic light emitting display device can be widely classified into a polymer device using a wet process, and a small molecule device using a deposition process. As a method for patterning a polymer or small molecule emission layer, an inkjet printing method is applied using limited materials for organic layers except for the emission layer, and has a complicated structure to be applied to a substrate. Further, a metal mask is needed to pattern the emission layer by the deposition process, so that there is much trouble in fabricating a large-sized device.
Meanwhile, a laser-induced thermal imaging (LITI) method has been recently developed as an alternative to the foregoing patterning method. The laser-induced thermal imaging method converts laser light from a light source into heat energy, and uses the heat energy to transfer a pattern forming material to an objective substrate, thus forming a pattern on the substrate. In the laser-induced thermal imaging method, a donor substrate formed with a transfer layer, a light source and an objective substrate are needed. Further, in the laser-induced thermal imaging method, the donor substrate and the objective substrate are laminated so that the donor substrate is adhered to the highest portion of the objective substrate.
However, in typical LITI processes for forming an organic light emitting display device, a large gap exists between the donor substrate and the pixel electrode. This large gap requires more laser energy for the LITI process, leading to damage and deterioration of the organic emission layer. Therefore, what is needed is an improved structure where this large gap is not apt to occur.